Chelsea took three vital league points at the Stadium of Light but almost suffered heart-failure by conceding a last-gasp goal.
The Blues ran out 1-2 winners but only just.
Thankfully by the time Ji Dong-Won slotted home a 91 minute goal, captain John Terry and hitman Daniel Sturridge had already done the damage.
Terry had two chances to ram home the opening goal on 16 minutes, the second coming courtesy of a rebound off Titus Bramble.
The centre-back gleefully rifled home from an acute angle past hapless Simon Mignolet.
The visitors dominated the remainder of the half but almost let one in two minutes from the break but Petr Cech was quick to smother Stephane Sessegnon’s low drive.
With only four minutes of the restart gone, Nicolas Anelka sent Sturridge through with an inch-perfect through ball. The striker shook off the attention of Wes Brown and then produced a remarkable back-heeled flick that flummoxed Mignolet and the ball trickled into the net.
Chelsea took the foot off the pedal after that and with tiredness creeping in looked to run the clock down.
But the Black Cats got a late, late goal that had the home side cheering and the away fans biting their nails.